Many space-based science missions require “next generation” on-board processing capabilities to meet the specified goals of each mission. These missions use advanced instrumentation systems such as laser altimeter, radar, lidar, and hyper-spectral instruments, which require advanced on-board processing capabilities to facilitate the timely conversion of planetary or earth science data into planetary or earth science information. Currently available processing systems do not have the processing power required by these advanced information systems. Both an “order of magnitude” increase in processing power and the ability to “reconfigure on the fly” are required to implement algorithms that detect and react to events, to produce data products on-board for applications such as direct downlink, quick look, and “first responder” real-time awareness, to enable “sensor web” multi-platform collaboration, and to perform on-board “lossless” data reduction by migrating typical ground-based processing functions on-board, thereby reducing on-board storage and downlink requirements.
The SpaceCube™ is a Field Programmable Gate Array (FPGA) based on-board science data processing system developed at the US Government's NASA Goddard Space Flight Center (GSFC). The goal of the SpaceCube program is to provide one to two orders of magnitude improvements in on-board computing power while lowering relative power consumption and cost. The SpaceCube design strategy incorporates commercial radiation-tolerant FPGA technology and couples it with an upset mitigation software architecture to provide “order of magnitude” improvements in computing power over traditional radiation-hardened flight systems.
Achieving these goals will require using newly available FPGA and other devices which have increased numbers of input and output (I/O) pins, and mounting these devices on both sides of each printed circuit board (PCB). Equipment area is a valuable commodity on space missions; therefore, it is also important to keep the PC boards as small as possible and to increase the part density mounted on each board. Large improvements in processing capability leads to use of processing elements that require significant increase of the number of external interconnections needed on the processor boards. The existing connectors used for space flight do not provide the density of contacts needed to provide the increased interconnect requirements of the improved processing boards.
It is important to use high quality printed circuit boards (PCB) in equipment included in space missions. A PCB is an assembly that mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from sheets of conductive material, typically copper or other suitable conductive metals, laminated onto a non-conductive substrate. To achieve a very high quality, PCBs intended for space flight are typically designed to meet industry quality standards such as IPC 6012B Class 3/A. IPC is a standards developing organization accredited by the American National Standards Institute whose aim is to standardize the manufacture of electronic equipment. Having a high quality PCB manufactured to well defined and trusted standards gives the customer a higher confidence that the PCB will survive the environmental stresses found in space and meet its life requirements. Until recently, designing to the Class 3/A standard has not been much of a problem. Modern PCBs often have multiple layers of conductive material and non-conductive substrate to allow routing of higher numbers of signals on densely populated boards. Designers typically use one side of the PCB for the majority of parts, and these “older” parts are in packages that make it fairly easy to meet the Class 3/A requirement. However, it is becoming more of a standard to use both sides of the board in order to reduce mass and increase performance. In addition, part manufacturers are cramming more I/O pins into packages and increasing the pin density per square inch. This makes designing to the Class 3/A quality standard difficult, especially for packages that contain 100 to 2000 pins. Using standard practices for building new-age space flight circuit boards currently adopted by space equipment providers such as GSFC makes it impossible to meet the Class 3/A requirements. PCB designs typically run into difficulty where changes made to meet one aspect of the Class 3/A standard cause other aspects to be violated thereby making it difficult and often impossible to meet the full requirements of the standard.
Accordingly, it would be desirable to provide a circuit board that address at least some of the problems identified above.